Hollow metal heads for golf clubs of the type known as "woods" have become extremely popular within the sport of golf. These are commonly referred to by the term "metal woods", which we shall use herein for convenience. Also for convenience, we shall use this term to include newer high-technology hollow club heads that are gaining favor in some golfing circles, such as so-called "graphite heads", which are actually made from a resinous material reinforced with fibers of carbon or graphite and formed by various means including winding resin-impregnated fibers on a mandril or forming in a mold sheets of resin-impregnated fiber mats, which processes are performed before the resin is fully cured.
Metal woods present numerous options to the golf club manufacturer to provide customized weight and balance for the golfer, whether he be an amateur or a professional. All golfers, to improve accuracy and precision of their golf shots, seek a club with an enlarged "sweet spot" (that area of the striking face that, upon striking the ball, will send the ball on a preferred trajectory, without "hooking" or "slicing"). In addition, modern golfers prefer a club head that is generally lightweight but with a significant portion of its weight behaving as if it were located behind the sweet spot. The hollow metal head of a metal wood offers the opportunity to engineer these desired features into the golf club.
A problem that occurs when one produces a hollow club head is that the flattened striking surface, which is supported around the edge thereof, acts much as a drum head when it is struck. The thin metal is free to deflect elastically upon impact and then rebound. The nature and direction of the rebound depends upon the location of the point of impact on the striking surface and can affect the speed, rotation, and direction of a golf ball as it leaves the club-head, thereby affecting the trajectory of the ball. Many inventors in the past have pointed to the desirability of having a totally inelastic, rigid striking surface on a golf club head. Some inventors have included in wooden golf club heads, rather thick metal inserts as the striking surface to produce a harder, more rigid contact surface. Others have even proposed glass and ceramic striking surfaces for club heads to achieve the same end. Of course, as in most all endeavors, there are nay-sayers who want to go in the other direction and have the striking surface capable of elastic deflection to offer more "spring" to the face, thereby (in their argument) to increase the rebound and make the ball go farther when it is struck. After testing various approaches, the applicant has decided in favor of the rigid, unyielding striking surface as the more desirable end product.
Many variations of metal woods have appeared on the market and in the patent literature. Applicant has seen none that offer the features of the present invention.